Gas turbine engines typically include a plurality of sections which are mounted in series. Typically a fan delivers air to a compressor. Air is compressed in the compressor and delivered downstream to be mixed with fuel and combusted in a combustor section. Products of combustion move downstream over turbine rotors. The turbine rotors include a plurality of blades which rotate with the rotors, and are driven by the products of combustion. The turbine rotors drive components within the gas turbine engine, including the fan and compressor.
Blades such as those used in turbines or other sections of the gas turbine engine can become hot during operation of the engine. In one example cooling technique known as “film cooling,” cooling air is passed through internal passages of the turbine blade, through holes in the surface of the turbine blade, and along an outer face of the turbine blade. The volume of air used as cooling air reduces air available for combustion, and effects engine efficiency.